Glossary beginning with L

Volcano Term Definitions


A body of igneous rocks with a flat bottom and domed top. It is parallel to the layers above and below it.


A torrential flow of water-saturated volcanic debris down the slope of a volcano in response to gravity. A type of mudflow.


A series of unmanned satellites orbiting at about 706 km (438 miles) above the surface of the earth. The satellites carry cameras similar to video cameras and take images or pictures showing features as small as 30 m or 80 m wide, depending on which camera is used.


Literally "little stones." Round to angular rock fragments, measuring 1/10 inch to 2 1/2 inches in diameter, which may be ejected in either a solid or molten state.


Magma which has reached the surface through a volcanic eruption. The term is most commonly applied to streams of liquid rock that flow from a crater or fissure. It also refers to cooled and solidified rock.

Lava Dome

Mass of lava, created by many individual flows, that has built a dome-shaped pile of lava.

Lava Flow

An outpouring of lava onto the land surface from a vent or fissure. Also, a solidified tongue like or sheet-like body formed by outpouring lava.

Lava Fountain

A rhythmic vertical fountainlike eruption of lava.

Lava Lake

A lake of molten lava, usually basaltic, contained in a vent, crater, or broad depression of a shield volcano.

Lava Shield

A shield volcano made of basaltic lava.

Lava Tube

A tunnel formed when the surface of a lava flow cools and solidifies while the still-molten interior flows through and drains away.

Limu O Pele

Delicate, translucent sheets of spatter filled with tiny glass bubbles.


Of or pertaining to stone.


The rigid crust and uppermost mantle of the earth. Thickness is on the order of 60 miles (100 km). Stronger than the underlying asthenosphere.


The reflection of light from the surface of a mineral.